ALLEN GLACIER AND OTHER ICE TONGUES 447
and Miles Glaciers do, the canyon is open, having only this one large glacier extending into it, and this ice tongue reaches only about a mile into the Copper River valley. The other glaciers of t.hia portion of Copper River end at a considerable height in the mountains.
General Description. This ice tongue rises in cirques and snowfields 4000 to 6000 feet above sea level. It has a known length of about 8 miles and perhaps an even greater extension in the mountains. At the mouth of its mountain valley it has a width of about a mile. Outside the mountain valley it expands in a bulb over two miles wide, and originally similar in form to the bulb of Allen Glacier. The bulb of Heney Glacier has now been modified by retreat, but more is left of it than that of Childs Glacier, because Copper River has not cut into the Heney and modified its form.
McCune Glacier, a former tributary of Heney Glacier on the south side, erroneously shown on previous maps as confluent with Heney Glacier, has been disconnected from the main ice tongue by melting and now terminates about half a mile within its valley.
Heney Glacier terminates in a low slope, most of which is covered with ablation moraine and supports thick vegetation. In front of the glacier is an abandoned terminal moraine, traversed in a great curve by the railway. Between the railway and the glacier there are several lakes, the shores of two of which are traversed by the railway. In the largest one, which is farthest to the north, the glacier has a vertical cliff and discharges a few small icebergs. Heney Glacier is nearly as large as Childs Glacier, but is much less impressive as seen from the railway, because it is not so active, and has not a high vertical cliff undercut by the Copper River. Because it is moving slowly, the outer end of it is dark-colored and unattractive, with ablation moraine and ice covered with thickets of alder and cottonwood. The upper part of the glacier is clean and beautiful and a view from a point about a mile west of the railway shows Heney Glacier as an impressive and attractive tongue of ice, ranking fully with the Childs Glacier in size and beauty.
Precious Maps. Heney Glacier has not been described previously. It was first shown upon a map by Mahlo in 1898.1 It was sketched more accurately by Witherspoon in 1900 * (PL CLXXIX) and was shown upon a later map of the U. S. Geological Survey.* The detailed map of tne terminal bulb (PL CLXXVHI) was made in 1910 by the National Geographic Society's expedition. Rough sketches of the relationship of the glacier terminus were made by the railway surveyors between 1906 and 1909, and their maps are the first ones upon which the presence of the lakes in front of Heney Glacier is shown. Throughout this period of observation, this ice tongue seems to have remained in about the same position and condition, and it may be assumed to have been inactive, with normal slow motion in the valley glacier and tributaries, and with an almost stagnant condition in the bulb, from sometime before 1898 to the summer of 1910 when our studies were made.
The Valley Glacier. The valley glacier showed no abnormal features in 1910. It heads on a snow divide with the Schwan Glacier of Tasnuna valley, flowing eastward and receiving as tributaries two cascading glaciers from the west and two large and two small glaciers from the south. The slope of the main ice tongue is moderate, an ascent
i Abercrombie, W. R., .War Dep't., Adj.-Gen. Office, No. XXV, Washington, 1899; Schrader, F. C., 20th Ann. Rept, U. S. Geol. Survey, Part VII, 1900, Map No. 21. > House Doc. 546,56th Congress, 2nd Session, Washington, 1900, PI. II. »Bull. 374, U. S. Geol. Survey, 1909. PI. I.